Protecting images with multiple image watermarks

ABSTRACT

The present invention provides methods and apparatus for imparting a multiplicity of watermarks onto a digitized image. The image includes a plurality of pixels, wherein each of the pixels includes brightness data that represents one brightness value if the image is monochrome, or a plurality of brightness data values if the image has multiple colors. In one aspect it provides for imparting more than one watermark into the digitized image comprising the steps of providing the digitized image, and multiplying the brightness data associated with at least one of the image pixels by a plurality of predetermined brightness multiplying value. Another aspect of the present invention is to provide a method for generating a composite watermark and imparting on a plurality of copies of a digitized image a different composite watermark into each copy. Also provided is a method for detecting one or more of the watermarks in the composite.

PRIORITY

[0001] This application claims priority from Provisional application,having the same title and inventorship, assigned Serial No. 60/299,822,filed, Jun. 21, 2001.

FIELD OF THE INVENTION

[0002] This application relates to the field of digital imaging. It ismore specifically concerned with the insertion and detection ofidentifying marks on a work-piece.

BACKGROUND OF THE INVENTION

[0003] It is a constant endeavor to find improved techniques of placingvisible or invisible identifying marks on an image. This is generallyuseful to establish ownership, origin and authenticity, and also todiscourage those who might wish to purloin or misappropriate the work.Identifying marks are also useful to give evidence of unauthorizedalteration or disclosure. All heretofore watermarking methods areconcerned with imparting a single watermark. There are advantages inimparting a composite watermark of a multiplicity of watermarks andhenceforth detecting one or more watermarks from the multiplicity.

[0004] Invisible marks are herein classified relative to the appearanceof that mark to a human being with normal visual acuity. A mark on animage is classified as having an invisibility classification level ofundetectable invisible if, when the image without the marking isdisplayed together with an image copy with the marking, the human beingis equally likely to select either of these copies. An undetectableinvisible mark is below or at the human being's just-noticeabledifference. A mark on an image is classified as having an invisibilityclassification level of subliminally invisible if the mark is notdistracting to the human being, although it is above the human being'sjust-noticeable difference. An image marking is classified as beingmarginally invisible if it does not cause the marked image to lose itsusefulness or value because of the mark. An image marking is classifiedas being poorly invisible if the marking causes a reduction in theimage's usefulness and/or value.

[0005] Presently, invisible markings of hard copy documents are used asa generally dependable method of establishing ownership andauthenticity. These time-tested methods are also useful for marking a“soft copy” digitized image, also referred to herein as a digital imageor image. A digital image is an abstraction of a physical image that hasbeen scanned and stored in a computer's memory as rectangular arrays ofnumbers corresponding to that image's (one or more) color planes. Eacharray element corresponding to a very small area of the physical imageis called a picture element, or pixel. The numeric value associated witheach pixel for a monochrome image represents the magnitude of itsaverage brightness on its single color (black and white) plane. For acolor image, each pixel has values associated and representing themagnitudes or average brightness of its tristimulus color componentsrepresenting its three color planes. Other image representations havemore than three color components for each pixel. A different value isassociated with each different one of the image's color planes.

[0006] Whenever reference is made herein to color planes, it isunderstood to include any number of color planes used by a particularimage's digitizing technique to define the pixel's colorcharacteristics. This includes the case when there is only a singleplane defining a monochromatic image.

[0007] Generally, a digitized image is recognizable as an image to aviewer only when the individual pixels are displayed as dots of white orcolored light on a display or as dots of black or colored inks or dyeson a hard copy. Pixels are normally spaced so closely as to be notresolvable by a human visual system. This results in the fusion ofneighboring pixels by the human visual system into a representation ofthe original physical image. Image fusion by the human visual systemmakes invisible marking, or relatively invisible marking, of imagespossible. This property is fully exploited by the methods described hereto both impart upon a digitized image an invisible watermark to adesired invisibility classification, and to subsequently demonstrate itsexistence. The imparting and demonstrated detection of a robustinvisible marking on digital images, herein called invisiblewatermarking, are a primary aspect of the present invention.

PROPERTIES OF A ROBUST INVISIBLE WATERMARK

[0008] A proper invisible watermarking technique that imparts aninvisible watermark upon a proprietary digitized image should satisfyseveral properties. The imparted watermark should appear to be invisibleto any person having normal or corrected visual accommodation to adesired invisibility classification level. Clearly, the degree ofmarking is a dichotomy. A balance has to be struck between protectingthe image from unauthorized uses and not having the watermarkunpleasantly alter the appearance of the image. This generally meansthat a recognizable pattern should not appear in the marked image whenthe watermark is applied to a uniform color plane. This requirementdiscourages marking the image by varying the hue of its pixels, sincethe human visual system is significantly more sensitive to alterationsin hue than in brightness. The requirement can be satisfied by atechnique based on varying pixel brightness implemented in a proper way.A technique based on varying pixel brightness also allows the samemarking technique applied to color images to be equally applicable tomonochrome images.

[0009] Another property of a proper invisible watermarking technique isthat it should have a detection scheme such that the probability of afalse-positive detection, that is, the false detection of a mark whenone, in fact, does not exist, is vanishingly small. For purposes of thepresent invention, the probability of detection of a watermark in animage when one does not exist should be less than one in a million.There is generally little difficulty satisfying this requirement whenthe technique is statistically based.

[0010] Still another property of a proper watermarking technique is thatit should be possible to vary the degree of marking applied to an image.In this way, the watermark can be made as detectable as necessary by theparticular application. This property is important in highly texturedimages where it is often necessary to increase the intensity of the markto increase its likelihood of detection. This is in contradistinctionwith images that have low contrast in which it is advantageous to reducethe marking intensity to lessen undesirable visible artifacts of thewatermark itself.

[0011] Finally, the imparted watermark should be robust in that itshould be very difficult to be removed or rendered undetectable. Itshould survive such image manipulations that in themselves do not damagethe image beyond usability. This includes, but is not limited to, JPEG“lossy” compression, image rotation, linear or nonlinear resizing,brightening, sharpening, “despeckling,” pixel editing, and thesuperposition of a correlated or uncorrelated noise field upon theimage. Attempts to defeat or remove the watermark should be generallymore laborious and costly than purchasing rights to use the image. Ifthe image is of rare value, it is desirable that the watermark be sodifficult to remove that telltale traces of it can almost always berecovered. It is noted that various visible and invisible watermarkingtechniques are know to those skilled in the art. Each techniquegenerally has different advantages and satisfying different levels ofrobustness, security and adaptability. Many of these employ particularalgorithms in determining how the pixel date of pixels in the originalunmarked digitized image is to be modified in order to include theparticular watermark. In general, each watermark importing technique hasa corresponding watermark detecting technique. The common feature ofmany of these techniques is that the pixel data is ultimately modifiedin a particular way.

[0012] It would be advantageous to have a watermarking technique whichwould enable imparting a multiplicity of watermarks one at a time, ingroups, and/or a group of watermarks all at once. The totality of themultiplicity of watermarks are herein referred to a composite watermark.Each of the separate watermarks is a part of the composite watermark. Itwould also be advantageous to have a watermarking technique which wouldenable detecting the imparted multiplicity of watermarks one at a time,in groups, and/or a group of watermarks all at once.

SUMMARY OF THE INVENTION

[0013] It is therefore an aspect of the present invention to providemethods, systems and apparatus for imparting a multiplicity ofwatermarks into a digitized image including the steps of providing thedigitized image, and multiplying the brightness data associated with atleast one of the image pixels by a plurality of predetermined brightnessmultiplying values.

[0014] In another aspect of a general embodiment, the brightness valuesof all image pixels or all image pixels in a specified image portion,are multiplied by an associated brightness multiplying value.

[0015] In another particular embodiment, each of the pixels has a rowand a column location in an array representing the digitized image, andeach brightness multiplying value employs a different sequentialcombination of numbers from a different robust random number sequence insequential correspondence to the row and column location.

[0016] Another aspect of the present invention is to provide a methodfor generating a composite watermarked image wherein watermarks areimparted into a digitized image having a plurality of original elements.Each of the elements having original brightness values.

[0017] Another aspect of the present invention is to provide a methodfor forming composite watermarking planes. Each watermarking plane inthe composite including a plurality of elements with element having amultiplying value.

[0018] Another aspect of the present invention is to provide methods andapparatus which would enable detecting the imparted multiplicity ofwatermarks one at a time, in groups, and/or a group of watermarks all atonce.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] These and other aspects, features, and advantages of the presentinvention will become apparent upon further consideration of thefollowing detailed description of the invention when read in conjunctionwith the drawing figures, in which:

[0020]FIG. 1 shows a block diagram of an example of a method ofgenerating multiple composite watermarking planes for imparting intomultiple image copies in accordance with an embodiment of the presentinvention.

[0021] FIGS. 2(a) and 2(b) together show an example of a flow diagramfor detecting a particular composite watermark from an image copysuspected of having an imparted watermark in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention provides methods, systems and apparatus forimparting upon a digitized image a multiplicity of watermarks one at atime, in a group, in a plurality of groups, and/or a group of watermarksall at once. The totality of the multiplicity of watermarks are hereinreferred to a composite watermark. Each of the separate watermarks is apart of the composite watermark.

[0023] Generally, the image includes a plurality of pixels, wherein eachof the pixels includes brightness data that represents one brightnessvalue if the image is monochrome, or a plurality of brightness datavalues if the image has multiple colors.

[0024] In an exemplary embodiment, the present invention provides thesemethods, systems and apparatus for imparting the multiplicity ofwatermarks into a digitized image including the steps of providing thedigitized image, and multiplying the brightness data associated with aplurality of the image pixels by a plurality of predetermined brightnessmultiplying values. A multiplying value is also called a factor or amultiplying factor. In a most general embodiment, the brightness valuesof all image pixels or all image pixels in a specified image portion,are multiplied by an associated brightness multiplying value.

[0025] The brightness multiplying values range from zero to unity. In anadvantageous embodiment the brightness multiplying values range from 0.8to 1.0. In a more particular embodiment, each of the several brightnessmultiplying values has a relationship with a number taken from adifferent random number sequence and the relationship is a linearremapping to provide a desired modulation strength. The modulationstrength is generally between zero and unity. In some embodiments it ismore than zero but less than 0.8.

[0026] In another particular embodiment, each of the pixels has a rowand a column location in an array representing the digitized image, andeach brightness multiplying value employs a different sequentialcombination of numbers from a different robust random number sequence insequential correspondence to the row and column location.

[0027] The present invention is adaptable for use of any of manywatermarking techniques. It is most particularly adaptable to awatermarking technique employing a watermarking plane. Thus, althoughthe present invention is adaptable to many watermarking techniques, itis most easily described and adaptable to the watermark imparting anddetecting methods described in U.S. Pat. No. 5,530,759 and U.S. Pat. No.5,825,892 which are herein included by reference in entirety for allpurposes. Methods and apparatus enable imparting and/or detecting theimparted multiplicity of watermarks one at a time, in groups, and/or agroup of watermarks all at once.

[0028] In still another particular embodiment, the present inventionprovides methods and apparatus for forming composite watermarkingplanes. Each watermarking plane in the composite watermarking planesincluding a plurality of elements with each element having a multiplyingvalue.

[0029] Specifically, in an exemplary embodiment, watermarks are imbeddedinto an image by multiplying the brightness of the components of eachpixel of the image by the linearly remapped values of the watermarkingplane, w(i,j), where 1>w(i,j)≧(1-2β), i is the value's row index, j isthe value's column index, and β is the modulation strength of thewatermark. More than one watermark can be imparted into an image bysequential applications of the methods of this invention. Each watermarkso imparted will be represented by a distinct watermarking planegenerated using its own distinct “robust-watermarking-parameters.” Ifthe quantity P of watermarking planes, designated w_(P)(i,j), eachhaving a modulation strength β_(p), for p=1, 2, . . . ,P, aresequentially imparted into an image, then each watermarking plane can bedetected by knowing only its unique robust-watermarking-parameters.

[0030] Using the mathematical property of association, a singlecomposite watermarking plane, w_(C)(i,j), can be constructed that is theelement-by-element product

w _(C)(i,j)=w ₁(i,j)·w ₂(i,j)· . . . ·w _(P)(i,j)

[0031] To a first order of approximation, the equivalent modulationstrength of the composite watermarking plane is the sum of themodulation strengths of its parts, or

β_(C)=β₁+β₂+ . . . +β_(P)

[0032] Applying several distinct watermarks to an image by using acomposite watermarking plane is useful for many applications. Forexample, if thirty distinct watermarking planes are generated, each withits own distinct “robust-watermarking-parameters,” and the thirty aredivided into three equal groups in such a manner that each watermarkingplane appears in only one group, then 1000 distinct compositewatermarking planes can be produced by using one watermarking plane fromeach of the three groups. If the 1000 composite watermarking planes areused to watermark 1000 copies of an image, subsequent detection of thesingle composite mark requires no more than thirty detection attemptsusing each of the thirty distinct watermarking planes. Since eachdistinct watermarking plane of a composite watermarking is itselfdetectable, a particular composite watermarking plane is also identifiedby the detection of its three composite parts. Once the three compositeparts are individually detected, a final detection of the particularcomposite watermarking may be attempted as further verification of thecorrect identification of the one of 1000 distinct compositewatermarking planes. This is significantly more efficient than searchingfor the particular watermark by attempting detection of each of the 1000composite watermarking panes until the correct one is found. On average,detection of a particular composite watermarking plane will requirefifteen tries rather than 500, and a maximum of thirty tries rather than1000.

[0033] Applying more than one distinct watermark to an image is alsouseful when the set of “robust-watermarking-parameters” of one watermarkremain secret to a first entity while, for example, a second set isdivulged to another entity. The divulged parameter set could be used byan image copy recipient, a second entity, to detect the secondwatermark, but the secret watermark remains undetectable except by thefirst entity having knowledge of the secret parameter set used togenerate it.

[0034] As an example, referring to FIG. 1, thirty distinct watermarkingplanes are generated using the method of the present invention (101).Each of the thirty watermarking planes, designated as w_(P)(i,j), p=1,2, . . . , 30, is generated using its own distinct“robust-watermarking-parameters.” In this manner and as stated before,each watermarking plane can be reconstructed at any future time if itsdistinct “robust-watermarking-parameters” are then known. The thirtydistinct watermarking planes are arbitrarily divided into three equalgroups (103) with none of the thirty appearing in more than one group.Members of the three groups are designated as w_(q)(i,j), w_(r)(i,j),and w_(s)(i,j), respectively. Once divided, knowledge of the“robust-watermarking-parameters” corresponding to each group is retained(105), since reconstruction of the thirty watermarking planes from their“robust-watermarking-parameters” will be required for watermarkdetection at a later time. Using the three groups, 1000 distinctcomposite watermarking planes, designated w_(C)(i,j), are formed as theelement-by-element products of three distinct watermarking planes, onechosen from each of the three groups (107). The 1000 compositewatermarking planes are the maximum number of distinct combinations ofelements from the three groups. It is evident to those skilled in theart that 10,000 distinct composite watermarking planes could be formedin a similar manner from forty distinct watermarking planes separatedinto four equal groups.

[0035] The 1000 distinct composite watermarking planes can be used oneat a time to impart a distinct watermark into 1000 copies of a singleimage (109), using the method described in U.S. Pat. No. 5,825,892,included herein in its entirety, or other method.

[0036] Referring to FIGS. 2a and 2 b, wherein FIG. 2(b) is acontinuation of FIG. 2(a), if it is desired to determine whether one ofthe 1000 composite watermarks was used to impart a watermark into animage copy that is suspected of being one of the 1000 so watermarked(201), knowledge of the three groups of “robust-watermarking-parameters”saved during the watermarking process is recalled (203). An applicablemethod used for watermark detection is described in U.S. Pat. No.5,825,892, included herein by reference in its entirety. It is notnecessary to attempt watermark detection with each of the 1000 compositewatermarking planes until the correct one is found. Rather, thecomponent parts of the composite watermarking plane, namely the threewatermarking planes used in its construction, can be used individuallyinstead. This limits the search to not more than thirty tries, each tryusing one of the watermarking planes from the three groups.

[0037] The process is begun by choosing a previously unused set of“robust-watermarking-parameters” from the first group of ten sets (205).A unique watermarking plane is reconstructed from the chosen set ofparameters (207). Detection of the reconstructed watermarking plane inthe selected image copy is attempted, and if the detection issuccessful, the index of the set, q^(*), of“robust-watermarking-parameters” from the first set that was used toregenerate the watermarking plane is saved (209). If the presence of thereconstructed watermarking plane in the image copy is detected (211),the process proceeds to (215); otherwise a test is made to determine ifall ten of the first group sets of parameters have been used (213). Ifall ten have not been used, then steps (205) through (211) are repeateduntil either a detection is made (211) or all ten sets of parametershave been used (213). If no detection were made and all ten sets ofparameters have been tried, q^(*) is set to “not found” to reflect nodetection (214).

[0038] The process is continued by choosing a previously unused set of“robust-watermarking-parameters” from the second group of ten sets(215). A unique watermarking plane is reconstructed from the chosen setof parameters (217). Detection of the reconstructed watermarking planein the selected image copy is attempted, and if the detection issuccessful, the index of the set, r^(*), of“robust-watermarking-parameters” from the second set that was used toregenerate the watermarking plane is saved (219). If the presence of thereconstructed watermarking plane in the image copy is detected (221),the process proceeds to (225); otherwise a test is made to determine ifall ten of the second group sets of parameters have been used (223). Ifall ten have not been used, then steps (215) through (221) are repeateduntil either a detection is made (221) or all ten sets of parametershave been used (223). If no detection were made and all ten sets ofparameters have been tried, r^(*) is set to “not found” to reflect nodetection (224).

[0039] The process is further continued by choosing a previously unusedset of “robust-watermarking-parameters” from the third group of ten sets(225). A unique watermarking plane is reconstructed from the chosen setof parameters (227). Detection of the reconstructed watermarking planein the selected image copy is attempted, and if the detection issuccessful, the index of the set, s^(*), of“robust-watermarking-parameters” from the third set that was used toregenerate the watermarking plane is saved (229). If the presence of thereconstructed watermarking plane in the image copy is detected (231),the process proceeds to (235); otherwise a test is made to determine ifall ten of the third group sets of parameters have been used (233). Ifall ten have not been used, then steps (225) through (231) are repeateduntil either a detection is made (231) or all ten sets of parametershave been used (233). If no detection were made and all ten sets ofparameters have been tried, s^(*) is set to “not found” to reflect nodetection (234).

[0040] If the suspect image copy is in fact watermarked, on average,only five choices from each group of sets will be needed for a total offifteen attempted detections, and not more than thirty detections willever be needed. The indexes of the detected watermark from each of thethree groups are designated q^(*), r^(*) and s^(*), and the threedetected watermarking planes as w_(q) _(^(*)) (i,j), w_(r) _(^(*))(i,j), and w_(s) _(^(*)) (i,j). The distinct composite watermarking isdetermined by knowing q^(*), r^(*) and s^(*), and is w_(C) _(^(*))(i,j)=w_(q) _(^(*)) (i,j)·w_(r) _(^(*)) (i,j)·w_(s) _(^(*)) (i,j). Ifq^(*), r^(*) and s^(*) exist, that is, if none of them is set to “notfound” (235), a further confirming verification can be done by detectingthe composite watermarking plane w_(C) _(^(*)) (i,j) (237), but,strictly speaking, it is not necessary. There can be only one compositewatermarking plane composed of the detected constituent parts designatedby w_(q) _(^(*)) (i,j) , w_(r) _(^(*)) (i,j) , and w_(s) _(^(*)) (i,j).

[0041] Those skilled in the art will recognize that there are detectionstrategies using the component parts of a composite watermark other thanthe strategy shown in the present example. These other strategies arewithin the scope and intent of the present invention.

[0042] In the present example, detection of only one of three distinctimparted watermarks is strong evidence of knowledge of its set ofwatermarking parameters, but 100 of the 1000 images copies would havethat imparted watermark and isolation to a single copy is not possibleby this means. Detection of only two of the three distinct impartedwatermarks is strong evidence of knowledge of the two sets ofwatermarking parameters, but ten of the 1000 image copies would havethose imparted watermarks and isolation to the single copy is notpossible by this means. Detection of all three distinct impartedwatermarks is strong evidence of knowledge of all three sets ofwatermarking parameters, and isolation to the distinct image copy fromthe 1000 watermarked image copies is achieved. Detection of threedistinct imparted watermarks, one from each group, is logicallyequivalent to detecting the single composite watermark that isconstructed using those three distinct watermarks as its componentparts.

[0043] It is noted that the composite watermark imparting and detectiontechnique of the present invention is usable with other watermarkimparting and detection techniques by sequentially applying the logicalequivalents of their watermarking planes, whether those equivalents liein the spatial pixel domain or in a transform domain (for example, aDiscrete Fourier transform domain or a Discrete Cosine transformdomain). A watermark may be factored into its associative componentequivalent watermarking planes or made to be an associative compositecombination on two or more of its component equivalent watermarkingplanes

[0044] An alternative method for imparting a single watermark or aplurality of watermarks into a digital image is accomplished by firstdefining an auxiliary monochrome image plane. The size of the monochromeimage plane is chosen such that pixels in the monochrome image planehave a one-to-one pixel correspondence with pixels of the digital image.The brightness values of pixels of the monochrome plane are choseninitially to be uniform in value and greater than zero. At least onewatermark is imparted into the monochrome image plane forming a firstwatermarking image. A plurality of watermarks are accomplished bysequentially imparting at least one other watermark into the monochromeimage plane forming another watermarking image. The brightness pixelvalues of said another watermarking image are linearly remapped suchthat all brightness values v(i,j) lie in a range 1>v(i,j)≧(1-2β_(C)),where i is the value's row index, j is the value's column index, andβ_(C) is the cumulative modulation strength of the plurality ofwatermarks. It will be apparent to those skilled in the art that v(i,j)is equivalent in form, meaning, and properties to the compositewatermarking plane, w_(C)(i,j), described previously, and v(i,j) cantherefore serve as an alternative form of a composite watermarkingplane. It will also be apparent to those skilled in the art that the anyimage watermarking method can be used to impart watermarks sequentiallyinto the auxiliary monochrome image plane that is subsequently used toform the linearly remapped values v(i,j).

[0045] Thus, the present invention provides methods and apparatuswherein the first brightness multiplying value imparts a watermark of afirst entity and at least one of said at least one subsequent brightnessmultiplying value imparts a watermark from one or more other entity;and/or wherein said element brightness multiplying value of saidwatermarking plane has a relationship with a number taken from a randomnumber sequence; and/or wherein said relationship is a linear remappingto provide a desired modulation strength; and/or wherein said modulationstrength is greater than 0 and less than 0.5; and/or wherein each ofsaid pixels has a row and a column location in an array representingsaid digitized image, and wherein said element of said watermarkingplane brightness multiplying value employs a different sequentialcombination of numbers from said random number sequence in sequentialcorrespondence to said row and column location; and/or wherein saidsequence is formed from a plurality of robust watermarking parameters;and/or wherein said parameters comprise a cryptographic key, at leasttwo coefficients and an initial value of said random number generator;and/or wherein at least one distinct watermark is a visible watermark;and/or further comprising forming an element of a composite watermarkingplane as the product of a first watermarking element chosen from adistinct watermarking plane from a single group of distinct watermarkingplanes, with at least one other watermarking element chosen from atleast one other distinct watermarking plane chosen from the same group;and/or wherein a cluster of up to one million unique compositewatermarking planes is formed by using distinct combinations of: a firstdistinct watermark plane taken from a first group of one hundreddistinct watermarking planes; a second distinct watermarking plane takenfrom a second group of one hundred distinct watermarking planes; and athird distinct watermarking plane taken from a third group of onehundred distinct watermarking planes.

[0046] Furthermore, a cluster of unique composite watermarks can beformed from a single group of distinct watermarks by using all possiblecombinations of the distinct watermarks two at a time, three at a time,or m at a time. For example, if the single group of distinct watermarksis composed of thirty distinct watermarks, a cluster of 4060 uniquecomposite watermarks can be formed using all possible combinations ofthe thirty distinct watermarks taken three at a time. Detection of aparticular composite watermarking plane will require a maximum of thirtytries rather than 4060.

[0047] Furthermore, the present invention provides methods and apparatusfor detecting a composite watermark imparted into a digitized image copyemploying a watermarking process, including the steps of: recallingthree groups of “robust-watermarking-parameters” saved during thewatermarking process; choosing a previously unused set of“robust-watermarking-parameters” from a first group of ten sets;reconstructing a first distinct watermarking plane using the chosen setof “robust-watermarking-parameters” from the first group of ten sets;attempting detection of the reconstructed first distinct watermarkingplane in the selected image copy; saving an index of the set, q^(*), of“robust-watermarking-parameters” from the first set that was used toregenerate the first distinct watermarking plane, w_(q) _(^(*)) (i,j),if the detection is successful, otherwise repeating the steps ofchoosing, reconstructing and attempting until all ten sets of“robust-watermarking-parameters” from the first group of ten sets areused, otherwise setting q^(*) to “not found” to reflect no detection ifthe detection using any set of “robust-watermarking-parameters” from thefirst group is not successful; choosing a previously unused set of“robust-watermarking-parameters” from a second group of ten sets;reconstructing a second distinct watermarking plane, w_(r) _(^(*))(i,j), using the chosen set of “robust-watermarking-parameters” from thesecond group of ten sets; attempting detection of the reconstructedsecond distinct watermarking plane in the selected image copy; saving anindex of the set, r^(*), of “robust-watermarking-parameters” from thesecond set that was used to regenerate the second distinct watermarkingplane if the detection is successful, otherwise repeating the steps ofchoosing, reconstructing and attempting until all ten sets of“robust-watermarking-parameters” from the second group of ten sets areused, otherwise setting r^(*) to “not found” to reflect no detection ifthe detection using any set of “robust-watermarking-parameters” from thesecond group is not successful; choosing a previously unused set of“robust-watermarking-parameters” from a third group of ten sets;reconstructing a third distinct watermarking plane, w_(s) _(^(*)) (i,j),using the chosen set of “robust-watermarking-parameters” from the thirdgroup of ten sets; attempting detection of the reconstructed thirddistinct watermarking plane in the selected image copy; and saving anindex of the set, s^(*), of “robust-watermarking-parameters” from thethird set that was used to regenerate the third distinct watermarkingplane if the detection is successful, otherwise repeating the steps ofchoosing, reconstructing and attempting until all ten sets of“robust-watermarking-parameters” from the third group of ten sets areused, otherwise setting s^(*) to “not found” to reflect no detection ifthe detection using any set of “robust-watermarking-parameters” from thethird group is not successful.

[0048] In some embodiments, the detection further includes calculatingcomposite watermarking elements, w_(C) _(^(*)) (i,j), from thesuccessful q^(*), r^(*) and s^(*) as w_(q) _(^(*)) (i, j)·w_(r) _(^(*))(i,j)·w_(s) _(^(*)) (i,j) , while using w_(q) _(^(*)) (i,j)=1 for q^(*)set to “not found”, w_(r) _(^(*)) (i,j)=1 for r^(*) set to “not found”,and w_(s) _(^(*)) (i,j)=1 for s^(*) set to “not found” for all i and j,to obtain a calculated reconstructed watermarking plane for in rangingfrom 1 to I, and j ranging from 1 to J; and/or confirming an existenceof the calculated composite watermarking plane in the image bysuccessfully detecting the calculated reconstructed watermarking plane.

[0049] In further embodiments, for detecting a composite watermarkimparted into a digitized image copy employing a watermarking process,the method includes the steps of: recalling M groups of“robust-watermarking-parameters” saved during the watermarking process,each group having N sets of unique elements; designating the groups asgroup(m), with 1≦m≦M, and the sets of elements in group(m) as E(m,n)with 1≦n≦N; selecting a group(m) not previously selected from among thesaid M groups; choosing a previously unused set of“robust-watermarking-parameters”, E(m,n), from the selected group(m);reconstructing an m^(th) distinct watermarking plane, w_(q(m)) _(^(*))(i,j), using the chosen previously unused set of“robust-watermarking-parameters”, E(m,n), from the selected group(m);attempting detection of the reconstructed m^(th) distinct watermarkingplane in the selected image copy; saving an index of the set, q(m)_(^(*)) , of “robust-watermarking-parameters” from the set E(m,n) thatwas used to regenerate the distinct watermarking plane, w_(q(m)) _(^(*))(i,j), if the detection is successful, otherwise repeating the steps ofchoosing, reconstructing and attempting until all N sets of“robust-watermarking-parameters” from the selected group(m) are used,otherwise if the detection is not successful setting q(m)* to “notfound” to reflect no detection being made using any set of“robust-watermarking-parameters” from the selected group(m); andrepeating the steps of selecting, choosing, reconstructing, attemptingand saving until all M groups have not used.

[0050] In some embodiments, the detection further includes calculatingcomposite watermarking elements, w_(C) _(^(*)) (i,j), from thesuccessful

q(1)^(*), q(2)^(*), . . . , and q(M)^(*)

[0051] as

w_(q(1)) _(^(*)) (i,j)·w_(q(2)) _(^(*)) (i,j)· . . . ·w_(q(M)) _(^(*))(i,j),

[0052] while using

w_(q(m)) _(^(*)) (i,j)=1 for all i and j

[0053] for any q(m) set to “not found”, to obtain a calculatedreconstructed watermarking plane for i ranging from 1 to I, and jranging from 1 to J; and/or confirming an existence of the calculatedcomposite watermarking plane in the image by successfully detecting thecalculated reconstructed watermarking plane; and/or wherein at least onewatermark is subliminally invisible.

[0054] Furthermore, the present invention provides an article ofmanufacture comprising a computer usable medium having computer readableprogram code means embodied therein for causing watermarking, thecomputer readable program code means in said article of manufacturecomprising computer readable program code means for causing a computerto effect the steps of a method of this invention.

[0055] Furthermore, the present invention provides a computer programproduct comprising a computer usable medium having computer readableprogram code means embodied therein for causing watermarking, thecomputer readable program code means in said computer program productcomprising computer readable program code means for causing a computerto effect the steps of a method of this invention.

[0056] Still further, the present invention provides a program storagedevice readable by machine, tangibly embodying a program of instructionsexecutable by the machine to perform method steps for watermarking, saidmethod steps comprising the steps of a method of this invention.

[0057] The present invention also provides methods and apparatus forimparting a plurality of watermarks onto a digital image including thesteps of: imparting a first watermark onto a monochrome plane, saidmonochrome plane having pixels with one-to-one pixel correspondence withpixels of said digital image and with said pixels of said monochromeplane initially having uniform pixel brightness values, said pixels ofsaid monochrome plane forming a first watermarking image; imparting atleast one other watermark upon said first watermarking image forminganother watermarking image; linearly remapping pixel brightness valuesof said another watermarking image such that all brightness values ‘bv’lie in a range 0≦bv≦1, forming a composite watermarking plane; andimparting said plurality of watermarks from said composite watermarkingplane into said digital image.

[0058] In some embodiments, the step of imparting said plurality ofwatermarks includes watermarks obtained by multiplying pixel brightnessvalue of each pixel in said digital image by a linearly remappedbrightness value of a corresponding pixel in said watermarking plane.

[0059] The present invention also provides methods and apparatus forobtaining a monochrome plane having monochrome pixels with one-to-onecorrespondence with image pixels of a digital image, said monochromepixels having uniform brightness values; imparting a first watermarkonto said monochrome plane in forming a first watermarked plane;imparting at least one other watermark onto said first watermarked planein forming another watermarked plane; and linearly remapping thebrightness values of said monochrome pixels such that all brightnessvalues ‘bv’ lie in a range 0≦bv≦1; and forming a composite watermarkingplane.

[0060] Some embodiments include imparting the composite watermarkingplane onto a digital image, said digital image having a plurality ofimage pixels, each image pixel having one-to-one corresponding with amonochrome pixel of said composite watermarking plane.

[0061] Some embodiments include detecting at least one distinctwatermark from a composite watermark imparted into a digitized image:obtaining said digitized image into which said composite watermarked wasimparted employing a particular watermarking process; and employingdetection steps associated with a detection technique for a watermarkimparted using said particular watermarking process.

[0062] The present invention can be realized in hardware, software, or acombination of hardware and software. The present invention can berealized in a centralized fashion in one computer system, or in adistributed fashion where different elements are spread across severalinterconnected computer systems. Any kind of computer system—or otherapparatus adapted for carrying out the methods described herein—issuitable. A typical combination of hardware and software could be ageneral purpose computer system with a computer program that, when beingloaded and executed, controls the computer system such that it carriesout the methods described herein. The present invention can also beembedded in a computer program product, which comprises all the featuresenabling the implementation of the methods described herein, andwhich—when loaded in a computer system—is able to carry out thesemethods.

[0063] Computer program means or computer program in the present contextmean any expression, in any language, code or notation, of a set ofinstructions intended to cause a system having an information processingcapability to perform a particular function either directly or afterconversion to another language, code or notation and/or reproduction ina different material form.

[0064] It is noted that the foregoing has outlined some of the morepertinent aspects and embodiments of the present invention. Thisinvention may be used for many applications. Thus, although thedescription is made for particular arrangements and methods, the intentand concept of the invention is suitable and applicable to otherarrangements and applications. For example, although reference is madeto an example having 1000 copies of an image, the methods are applicableto any small or large number of image copies. Each copy, or group ofcopies having a particular composite watermark. Furthermore, a compositewatermark is in some cases only actually and/or identifiably a singlewatermark. Similarly, although particular embodiments advantageouslyrefer to all distinct watermarking elements in all distinct watermarkingplanes, other embodiments employ the concepts of this invention oftenusing significantly less than all elements and/or less than allwatermarking planes. Also, the technique is useful for applying distinctmarks to a multiplicity of other than digitized images.

[0065] Thus, it will be clear to those skilled in the art that othermodifications to the disclosed embodiments can be effected withoutdeparting from the spirit and scope of the invention. The describedembodiments ought to be construed to be merely illustrative of some ofthe more prominent features and applications of the invention. Otherbeneficial results can be realized by applying the disclosed inventionin a different manner or modifying the invention in ways known to thosefamiliar with the art.

What is claimed is:
 1. A method comprising imparting a plurality ofwatermarks into a digitized image, including the steps of: providing thedigitized image having at least one image plane, each said image planebeing represented by an image array having brightness data for aplurality of pixels, each of said pixels having at least one colorcomponent and having a pixel position; representing each watermark fromthe plurality of watermarks as being a distinct watermarking planerepresented by an array having a plurality of distinct watermarkingelements, each of said distinct watermarking elements having an arrayposition, said array position having one-to-one array positioncorrespondence with said pixel position of a particular pixel of saidimage pixels, and multiplying said brightness data associated with eachsaid at least one color component by a corresponding distinctwatermarking element from a subsequent distinct watermarking plane toproduce a composite watermarked pixel.
 2. A method as recited in claim1, wherein all of said distinct watermarking elements in each of saiddistinct watermarking planes are greater than 0.5 and less than 1 foreach of said pixels.
 3. A method as recited in claim 1, furthercomprising employing a predetermined brightness multiplying value beinga composite brightness multiplying value formed by combining a firstbrightness multiplying value and at least one subsequent brightnessmultiplying value.
 4. A method as recited in claim 1, wherein at leastone distinct watermarking plane is itself a composite watermarkingplane, wherein said composite watermarking plane is represented by anarray having a plurality of composite watermarking elements, each ofsaid composite watermarking elements having a composite array positionand having one-to-one composite array position correspondence with saidpixel position of said particular pixel of said image pixels.
 5. Amethod as recited in claim 4, further comprising forming each compositewatermarking element as the product of a first distinct watermarkingelement from a first distinct watermarking plane and at least one otherdistinct watermarking element from at least one other distinctwatermarking plane.
 6. A method as recited in claim 1, furthercomprising constructing a first distinct watermarking plane using afirst unique set of robust watermarking parameters, and constructing atleast one other distinct watermarking plane using at least one otherunique set of robust watermarking parameters.
 7. A method as recited inclaim 1, further comprising: gathering at least one distinctwatermarking plane into a first group, gathering at least one otherdistinct watermarking plane into at least one other group, and formingan element of a composite watermarking plane as the product of a firstwatermarking element chosen from a distinct watermarking plane from thefirst group with at least one other watermarking element chosen from atleast one other distinct watermarking plane chosen from said at leastone other group.
 8. A method as recited in claim 7, wherein the numberof distinct watermarking planes in the first group is ten and the numberof distinct watermarking planes in each of said at least one other groupis also ten, and wherein the number of groups is three.
 9. A method asrecited in claim 4, wherein a cluster of 1000 unique compositewatermarking planes is formed by using: all possible combinations of onedistinct watermark plane taken from a first group of ten distinctwatermarking planes; a second distinct watermarking plane taken from asecond group of ten distinct watermarking planes; and a third distinctwatermarking plane taken from a third group of ten distinct watermarkingplanes.
 10. A method as recited in claim 1, wherein each of 1000 copiesof the digitized image has imparted into it a unique composite watermarkby using a particular one of 1000 unique composite watermarking planesfrom a cluster of 1000 composite watermarking planes.
 11. A method asrecited in claim 2, wherein the first brightness multiplying valueimparts a watermark of a first entity and at least one of said at leastone subsequent brightness multiplying value imparts a watermark from atleast one other entity.
 12. A method as recited in claim 1, wherein saidelement brightness multiplying value of said watermarking plane has arelationship with a number taken from a random number sequence.
 13. Amethod as recited in claim 12, wherein said relationship is a linearremapping to provide a desired modulation strength.
 14. A method asrecited in claim 13, wherein said modulation strength is greater than 0and less than 0.5.
 15. A method as recited in claim 12, wherein each ofsaid pixels has a row and a column location in an array representingsaid digitized image, and wherein said element of said watermarkingplane brightness multiplying value employs a different sequentialcombination of numbers from said random number sequence in sequentialcorrespondence to said row and column location.
 16. A method as recitedin claim 12, wherein said sequence is formed from a plurality of robustwatermarking parameters.
 17. A method as recited in claim 16, whereinsaid parameters comprise a cryptographic key, at least two coefficientsand an initial value of said random number generator.
 18. A method asrecited in claim 1, wherein at least one distinct watermark is a visiblewatermark.
 19. A method comprising detecting a composite watermarkimparted into a digitized image copy employing a watermarking process,including the steps of: recalling three groups of“robust-watermarking-parameters” saved during the watermarking process;choosing a previously unused set of “robust-watermarking-parameters”from a first group of ten sets; reconstructing a first distinctwatermarking plane using the chosen set of“robust-watermarking-parameters” from the first group of ten sets;attempting detection of the reconstructed first distinct watermarkingplane in the selected image copy; saving an index of the set, q^(*), of“robust-watermarking-parameters” from the first set that was used toregenerate the first distinct watermarking plane, w_(q) _(^(*)) (i,j),if the detection is successful, otherwise repeating the steps ofchoosing, reconstructing and attempting until all ten sets of“robust-watermarking-parameters” from the first group of ten sets areused, otherwise setting q^(*) to “not found” to reflect no detection ifthe detection using any set of “robust-watermarking-parameters” from thefirst group is not successful; choosing a previously unused set of“robust-watermarking-parameters” from a second group of ten sets;reconstructing a second distinct watermarking plane, w_(r) _(^(*)) usingthe chosen set of “robust-watermarking-parameters” from the second groupof ten sets; attempting detection of the reconstructed second distinctwatermarking plane in the selected image copy; saving an index of theset, r^(*), of “robust-watermarking-parameters” from the second set thatwas used to regenerate the second distinct watermarking plane if thedetection is successful, otherwise repeating the steps of choosing,reconstructing and attempting until all ten sets of“robust-watermarking-parameters” from the second group of ten sets areused, otherwise setting r^(*) to “not found” to reflect no detection ifthe detection using any set of “robust-watermarking-parameters” from thesecond group is not successful; choosing a previously unused set of“robust-watermarking-parameters” from a third group of ten sets;reconstructing a third distinct watermarking plane, w_(s) _(^(*)) (i,j),using the chosen set of “robust-watermarking-parameters” from the thirdgroup of ten sets; attempting detection of the reconstructed thirddistinct watermarking plane in the selected image copy; and saving anindex of the set, s^(*), of “robust-watermarking-parameters” from thethird set that was used to regenerate the third distinct watermarkingplane if the detection is successful, otherwise repeating the steps ofchoosing, reconstructing and attempting until all ten sets of“robust-watermarking-parameters” from the third group of ten sets areused, otherwise setting s^(*) to “not found” to reflect no detection ifthe detection using any set of “robust-watermarking-parameters” from thethird group is not successful.
 20. A method as recited in claim 19,further comprising: calculating composite watermarking elements, w_(C)_(^(*)) (i,j), from the successful q^(*), r^(*) and s^(*) as w_(q)_(^(*)) (i,j)·w_(r) _(^(*)) (i,j)·w_(s) _(^(*)) (i,j), while using w_(q)_(^(*)) (i,j)=1 for q^(*) set to “not found”, w_(r) _(^(*)) (i,j)=1 forto “not found”, and w_(s) _(^(*)) (i,j)=1 for s^(*) set to “not found iand j, to obtain a calculated reconstructed water ane for i ranging from1 to I, and j ranging from 1 to J.
 20. A method as recited in claim 19,further comprising confirming an existence of the calculated compositewatermarking plane in the image by successfully detecting the calculatedreconstructed watermarking plane.
 22. A method for detecting a compositewatermark imparted into a digitized image copy employing a watermarkingprocess, the method comprising the steps of: recalling M groups of“robust-watermarking-parameters” saved during the watermarking process,each group having N sets of unique elements; designating the groups asgroup(m), with 1≦m≦M, and the sets of elements in group(m) as E(m,n)with 1≦n≦N; selecting a group(m) not previously selected from among thesaid M groups; choosing a previously unused set of“robust-watermarking-parameters”, E(m,n), from the selected group(m);reconstructing an m^(th) distinct watermarking plane, w_(q(m)) _(^(*))(i,j), using the chosen previously unused set of“robust-watermarking-parameters”, E(m,n), from the selected group(m);attempting detection of the reconstructed m^(th) distinct watermarkingplane in the selected image copy; saving an index of the set, q(m)^(*),of “robust-watermarking-parameters” from the set E(m,n) that was used toregenerate the distinct watermarking plane, w_(q(m)) _(^(*)) (i,j), ifthe detection is successful, otherwise repeating the steps of choosing,reconstructing and attempting until all N sets of“robust-watermarking-parameters” from the selected group(m) are used,otherwise if the detection is not successful setting q(m)^(*) to “notfound” to reflect no detection being made using any set of“robust-watermarking-parameters” from the selected group(m); andrepeating the steps of selecting, choosing, reconstructing, attemptingand saving until all M groups have not used.
 23. A method as recited inclaim 22, further comprising: calculating composite watermarkingelements, w_(C) _(^(*)) (i,j), from the successful q(1)^(*), q(2)^(*), .. . , and q(M)^(*) as w_(q(1)) _(^(*)) (i,j)·w_(q(2)) _(^(*)) (i, j )· .. . w_(q(M)) _(^(*)) (i,j), while using w_(q(m)) _(^(*)) (i,j)=1 for alli and j for any q(m) set to “not found”, to obtain a calculatedreconstructed watermarking plane for i ranging from 1 to I, and jranging from 1 to J.
 24. A method as recited in claim 23, furthercomprising confirming an existence of the calculated compositewatermarking plane in the image by successfully detecting the calculatedreconstructed watermarking plane.
 25. A method as recited in claim 19,wherein at least one watermark is subliminally invisible.
 26. An articleof manufacture comprising a computer usable medium having computerreadable program code means embodied therein for causing watermarking,the computer readable program code means in said article of manufacturecomprising computer readable program code means for causing a computerto effect the steps of claim
 1. 27. A computer program productcomprising a computer usable medium having computer readable programcode means embodied therein for causing watermarking, the computerreadable program code means in said computer program product comprisingcomputer readable program code means for causing a computer to effectthe steps of claim
 1. 28. A program storage device readable by machine,tangibly embodying a program of instructions executable by the machineto perform method steps for watermarking, said method steps comprisingthe steps of claim
 20. 29. A method comprising imparting a plurality ofwatermarks onto a digital image including the steps of: imparting afirst watermark onto a monochrome plane, said monochrome plane havingpixels with one-to-one pixel correspondence with pixels of said digitalimage and with said pixels of said monochrome plane initially havinguniform pixel brightness values, said pixels of said monochrome planeforming a first watermarking image; imparting at least one otherwatermark upon said first watermarking image forming anotherwatermarking image; linearly remapping pixel brightness values of saidanother watermarking image such that all brightness values ‘bv’ lie in arange 0≦bv≦1, forming a composite watermarking plane; and imparting saidplurality of watermarks from said composite watermarking plane into saiddigital image.
 30. A method as recited in claim 29, wherein a step ofimparting said plurality of watermarks includes watermarks obtained bymultiplying pixel brightness value of each pixel in said digital imageby a linearly remapped brightness value of a corresponding pixel in saidwatermarking plane.
 31. An article of manufacture comprising a computerusable medium having computer readable program code means embodiedtherein for causing watermarking, the computer readable program codemeans in said article of manufacture comprising computer readableprogram code means for causing a computer to effect the steps of claim29.
 32. An article of manufacture comprising a computer usable mediumhaving computer readable program code means embodied therein for causingwatermarking, the computer readable program code means in said articleof manufacture comprising computer readable program code means forcausing a computer to effect the steps of claim
 30. 33. An article ofmanufacture comprising a computer usable medium having computer readableprogram code means embodied therein for causing watermarking, thecomputer readable program code means in said article of manufacturecomprising computer readable program code means for causing a computerto effect the steps of claim
 31. 34. A computer program productcomprising a computer usable medium having computer readable programcode means embodied therein for causing watermarking, the computerreadable program code means in said computer program product comprisingcomputer readable program code means for causing a computer to effectthe steps of claim
 29. 35. A program storage device readable by machine,tangibly embodying a program of instructions executable by the machineto perform method steps for watermarking, said method steps comprisingthe steps of claim
 29. 36. A method as recited in claim 1, furthercomprising forming an element of a composite watermarking plane as theproduct of a first watermarking element chosen from a distinctwatermarking plane from a single group of distinct watermarking planes,with at least one other watermarking element chosen from at least oneother distinct watermarking plane chosen from the same group.
 37. Amethod comprising: obtaining a monochrome plane having monochrome pixelswith one-to-one correspondence with image pixels of a digital image,said monochrome pixels having uniform brightness values; imparting afirst watermark onto said monochrome plane in forming a firstwatermarked plane; imparting at least one other watermark onto saidfirst watermarked plane in forming another watermarked plane; linearlyremapping the brightness values of said monochrome pixels such that allbrightness values ‘bv’ lie in a range 0≦bv≦1; and forming a compositewatermarking plane.
 38. A method as recited in claim 37, furthercomprising imparting the composite watermarking plane onto a digitalimage, said digital image having a plurality of image pixels, each imagepixel having one-to-one position correspondence with a monochrome pixelof said composite watermarking plane.
 39. A program storage devicereadable by machine, tangibly embodying a program of instructionsexecutable by the machine to perform method steps for watermarking, saidmethod steps comprising the steps of claim
 37. 40. A method as recitedin claim 4, wherein a cluster of up to 1 million unique compositewatermarking planes is formed by using distinct combinations of: a firstdistinct watermark plane taken from a first group of up to one hundreddistinct watermarking planes; a second distinct watermarking plane takenfrom a second group of up to one hundred distinct watermarking planes;and a third distinct watermarking plane taken from a third group of upto one hundred distinct watermarking planes.
 41. A method comprisingdetecting at least one distinct watermark from a composite watermarkimparted into a digitized image: obtaining said digitized image intowhich said composite watermarked was imparted employing a particularwatermarking process; and employing detection steps associated with adetection technique for a watermark imparted using said particularwatermarking process.
 42. A method comprising detecting a compositewatermark imparted into a digitized image copy employing a watermarkingprocess, including the steps of: recalling a plurality of groups ofwatermarking parameters saved during the watermarking process; choosinga previously first unused set of watermarking parameters from a firstgroup of watermarking parameter sets; reconstructing a first distinctwatermarking plane using said first unused set from the first groupwatermarking parameter sets in forming a reconstructed first distinctwatermarking plane; attempting detection of the reconstructed firstdistinct watermarking plane in the selected image copy; saving an indexof the first unused set, q^(*), of watermarking parameters from thefirst unused set if the detection is successful, otherwise repeating thesteps of choosing, reconstructing and attempting until all sets ofwatermarking parameters from the first group of ten sets are used,otherwise setting q^(*) to “not found” to reflect no detection if thedetection using any watermarking parameter set of watermarkingparameters from the first group is not successful; choosing a secondunused set of watermarking parameters from a second group ofwatermarking parameter sets; reconstructing a second distinctwatermarking plane, W_(r) _(^(*)) (i,j), using said second unused set ofwatermarking parameters from the second group of watermarking parametersets; attempting detection of the reconstructed second distinctwatermarking plane in the selected image copy; saving an index of theset, r^(*), of watermarking parameters from said a second unused set ifthe detection is successful, otherwise repeating the steps of choosing,reconstructing and attempting until all still unused sets ofwatermarking parameters from the second group of watermarking parametersets are used, otherwise setting r^(*) to “not found” to reflect nodetection if the detection using all sets of watermarking parametersfrom the second group is not successful; choosing a third unused set of“robust-watermarking-parameters” from a third group of watermarkingparameter sets; reconstructing a third distinct watermarking plane,w_(s) _(^(*)) (i,j), using the third unused set of watermarkingparameters from the third group of watermarking parameter sets;attempting detection of the reconstructed third distinct watermarkingplane in the selected image copy; and saving an index of the set, s^(*),of watermarking parameters from the third unused set if the detection issuccessful, otherwise repeating the steps of choosing, reconstructingand attempting until all of watermarking parameter sets from the thirdgroup of watermarking parameter sets are used, otherwise setting s^(*)to “not found” to reflect no detection if the detection using any set ofwatermarking parameters from the third group is not successful.
 43. Anarticle of manufacture comprising a computer usable medium havingcomputer readable program code means embodied therein for causingwatermarking, the computer readable program code means in said articleof manufacture comprising computer readable program code means forcausing a computer to effect the steps of claim
 40. 44. A computerprogram product comprising a computer usable medium having computerreadable program code means embodied therein for causing watermarking,the computer readable program code means in said computer programproduct comprising computer readable program code means for causing acomputer to effect the steps of claim
 40. 45. An article of manufacturecomprising a computer usable medium having computer readable programcode means embodied therein for causing watermarking, the computerreadable program code means in said article of manufacture comprisingcomputer readable program code means for causing a computer to effectthe steps of claim
 41. 46. A computer program product comprising acomputer usable medium having computer readable program code meansembodied therein for causing watermarking, the computer readable programcode means in said computer program product comprising computer readableprogram code means for causing a computer to effect the steps of claim41.
 47. A program storage device readable by machine, tangibly embodyinga program of instructions executable by the machine to perform methodsteps for watermarking, said method steps comprising the steps of claim41.
 48. An article of manufacture comprising a computer usable mediumhaving computer readable program code means embodied therein for causingwatermarking, the computer readable program code means in said articleof manufacture comprising computer readable program code means forcausing a computer to effect the steps of claim
 42. 49. A computerprogram product comprising a computer usable medium having computerreadable program code means embodied therein for causing watermarking,the computer readable program code means in said computer programproduct comprising computer readable program code means for causing acomputer to effect the steps of claim
 42. 50. A program storage devicereadable by machine, tangibly embodying a program of instructionsexecutable by the machine to perform method steps for watermarking, saidmethod steps comprising the steps of claim 42.